Deep throat revisited

It is actually called a Big Gulp, but got your attention!

I got this hood back in 2008, with the idea of using it on the lathe.  I never really was able to get it working well enough for me – just not enough draw from the dust extractor.

Think I might have just solved that problem.

This is the dust extractor I have just purchased, from Timbecon

Looks small in the picture, but it is quite the monster.  3HP, 2900cfm, 22.5″H₂O static pressure.  8″ inlet, 400L of dust collection capacity. $900.

I was watching a timelapse I made of a process on the CNC, and I’d occasionally come in with a shot of compressed air to keep the working area clean.  Occurred to me that this would be right where the big gulp would come into its own – firstly sitting behind the CNC, drawing air and therefore any airborne particles away from the cutter, the workshop, and me.  And secondly, to catch any and all dust that gets sprayed back when I do use the compressed air.

You may wonder why I don’t have collection right at the cutter –  two reasons.  Firstly, I don’t want to pull the small parts up and out from where they are cut during nesting operations (particularly when they are only held down by the vacuum table), and secondly, it gets in the way of the camera!  I still have a lot of refinement to go, but these sorts of things are popping into my head now the issue of dust extractor power has been taken care of.

Given I also now have capacity spare in the dust extractor (as mentioned, it can take 1×8″ (200mm) in, which is the same cross section as 4×4″ tubes simultaneously.  Using anything less than 4 is only restricting flow, it doesn’t mean that the one or two being used are suddenly given a huge power boost (sadly)), I can plan to do some simultaneous collecting – such as one collecting on, or near the tool and one down at floor level where shaving accumulate/can be swept (or kicked) towards etc.  If I don’t close the blast gates to every tool other than the one being used, that won’t cause a real problem either.  It is going to take a bit of planning to reroute the dust extraction system to maximise the flowrate, even if that means running a much larger trunk line, or dual smaller lines across the workshop.  Who would have thought a 4″ (100mm) pipe would be regarded as a smaller line?!

One thing I am going to work on, is positioning the dust extractor in one of the storage areas I have alongside the main shed, so I don’t loose any valuable floorspace in the main shed, and minimise noise (not that the unit is particularly noisy).  The unit is 2600mm high (mostly those bags), so I will have to work out how to make it work with a lot less head-room.  The main workshop has no trouble with that height, and even a lower roof would be ok (the bags could just press against the roof – it would decrease overall airflow, but not massively).  However, where I have to put it, this may prove a real test.  What I will need to do is come up with a way to allow that much air to pass through something that has a lot less overall height.  Pleated filters may work (increased surface area because of the pleats means less overall height required), but I want to see what else I can come up with.  Ballooning bags perhaps?  (same surface area, larger diameter, and therefore less height).

The other ‘issue’ I see, is drawing that much air out of a workshop draws the same amount of air in from outside.  Where it could be really hot (summer) or cold (winter) – neither of which is desirable.  So instead, my thought is to place a filtered vent from the area the extractor is stored back into the main workshop.  That way the shop air is recirculated, not lost.  So long as I am not then pumping micron-sized particles back into the workshop (which is what filters are for), I don’t see this would be a particular problem.

Watching the timelapse, I see a huge amount of sawdust on the floor of the workshop (bad collection practices).  I think that will become more and more an issue of the past.